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Physic
Q:
In a purely capacitive circuit the current:
A) leads the voltage by one-fourth of a cycle
B) leads the voltage by one-half of a cycle
C) lags the voltage by one-fourth of a cycle
D) lags the voltage by one-half of a cycle
E) is in phase with the potential difference across the plates
Q:
An ac generator produces 10 V (rms) at 400 rad/s. It is connected to a series RLcircuit (R= 17.3 , L= 0.025 H). The rms current is:A) 0.50 A and leads the emf by 30°B) 0.71 A and lags the emf by 30°C) 1.4 A and lags the emf by 60°D) 0.50 A and lags the emf by 30°E) 0.58 A and leads the emf by 90°
Q:
An RLCseries circuit is connected to an oscillator with a maximum emf of 100 V. If the voltage amplitudes VR, VL, and VCare all equal to each other, then VRmust be:
A) 33 V
B) 50 V
C) 67 V
D) 87 V
E) 100 V
Q:
An RLCseries circuit has L= 100 mH and C= 1 F. It is connected to a 1000-Hz source emf, and the voltage is found to lead the current by 75°. The value of Ris:A) 12.6 B) 126 C) 175 D) 1750 E) 1810
Q:
In an RLCseries circuit, which is connected to a source of emf, the current lags the voltage by 45°if:
Q:
An RLseries circuit is connected to an ac generator with a maximum emf of 20 V. If the maximum potential difference across the resistor is 16 V, then the maximum potential difference across the inductor is:
A) 2 V
B) 4 V
C) 12 V
D) 26 V
E) 36 V
Q:
An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50- resistor, a 400-mH inductor, and a 200-F capacitor. The rms voltage across the inductor is:A) 2.5 VB) 3.4 VC) 6.7 VD) 10.0 VE) 10.8 V
Q:
An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50- resistor, a 400-mH inductor, and a 200-F capacitor. The rms voltage across the capacitor is:A) 2.5 VB) 3.4 VC) 6.7 VD) 10.0 VE) 10.8 V
Q:
An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50-resistor, a 400-mH inductor, and a 200-F capacitor. The rms voltage across the resistor is:A) 2.5 VB) 3.4 VC) 6.7 VD) 10.0 VE) 10.8 V
Q:
An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50-resistor, a 400-mH inductor, and a 200-F capacitor. The rms current is:A) 0.125 AB) 0.135 AC) 0.18 AD) 0.20 AE) 0.40 A
Q:
An electric motor, under load, has an effective resistance of 30 and an inductive reactance of 40 . When powered by a source with a maximum voltage of 420 V, the maximum current is:A) 6.0 AB) 8.4 AC) 10.5 AD) 12 AE) 14 A
Q:
When the amplitude of the oscillator in a series RLCcircuit is doubled:
A) the impedance is doubled
B) the voltage across the capacitor is halved
C) the capacitive reactance is halved
D) the power factor is doubled
E) the current amplitude is doubled
Q:
A coil has a resistance of 60 and an impedance of 100 . Its reactance is:A) 40 B) 60 C) 80 D) 117 E) 160
Q:
An RLCseries circuit has R= 4 , XC= 3 , and XL= 6 . The impedance of this circuit is:A) 5 B) 7 C) 7.8 D) 9.8 E) 13
Q:
When the frequency of the oscillator in a series RLCcircuit is doubled:
A) the capacitive reactance is doubled
B) the capacitive reactance is halved
C) the impedance is doubled
D) the current amplitude is doubled
E) the current amplitude is halved
Q:
The impedance of the circuit shown is:A) 21 B) 50 C) 63 D) 65 E) 98
Q:
The impedance of an RLCseries circuit is definitely increased if:
A) Cdecreases
B) Lincreases
C) Ldecreases
D) Rincreases
E) Rdecreases
Q:
A resistor, an inductor, and a capacitor are connected in parallel to a sinusoidal source of emf. Which of the following is true?
A) The currents in all branches are in phase.
B) The potential differences across all branches are in phase.
C) The current in the capacitor branch leads the current in the inductor branch by 1/4 cycle.
D) The potential difference across the capacitor branch leads the potential difference across the inductor branch by 1/4 cycle.
E) The current in the capacitor branch lags the current in the inductor branch by 1/4 cycle.
Q:
In the diagram, the function y(t) = ymsin() is plotted as a solid curve. The other three curves have the form , where is between and . Rank the curves according to the value of , from the most negative to the most positive.A) 1, 2, 3B) 2, 3, 1C) 3, 2, 1D) 1, 3, 2E) 2, 1, 3
Q:
The reactance of a 35-F capacitor connected to a 400-Hz generator is:A) 0 B) 0.014 C) 0.088 D) 11 E) 71
Q:
A 45-mH inductor is connected to an ac source of emf with a frequency of 400 Hz and a maximum emf of 20 V. The maximum current is:
A) 0 A
B) 0.18 A
C) 1.1 A
D) 360 A
E) 2300 A
Q:
A 35-F capacitor is connected to an ac source of emf with a frequency of 400 Hz and a maximum emf of 20 V. The maximum current is:A) 0 AB) 0.28 AC) 1.8 AD) 230 AE) 1400 A
Q:
A 45-mH inductor is connected to an ac source of emf with a frequency of 250 Hz and a maximum emf of 20 V. If the voltage across the inductor is zero at time t = 0, what is the voltage at time t= 2.0 ms? Assume the phase constant is zero.A) -20 VB) -10 VC) 0 VD) 10 VE) 20 V
Q:
A 35-F capacitor is connected to an ac source of emf with a frequency of 250 Hz and a maximum emf of 20 V. If the voltage across the capacitor is zero at time t = 0, what is the voltage at time t= 3.0 ms? Assume the phase constant is zero.A) -20 VB) -10 VC) 0 VD) 10 VE) 20 V
Q:
The angular frequency of a certain RLCseries circuit is . A source of sinusoidal emf, with angular frequency , is inserted into the circuit and is varied while the amplitude of the source is held constant. For which of the following values of is the amplitude of the current oscillations the greatest?A) /5B) /2C) D) 2E) None of them (they all produce the same current amplitude)
Q:
The angular frequency of a certain RLCseries circuit is . A source of sinusoidal emf, with angular frequency 2, is inserted into the circuit. After transients die out the angular frequency of the current oscillations is:A) /2B) C) 1.5D) 2E) 3
Q:
An RLCcircuit has a resistance of 200 an inductance of 15 mH, and a capacitance of 34 nF. At time t= 0 the charge on the capacitor is 25 C and there is no current flowing. After five complete cycles the energy stored in the capacitor is:A) 0.64JB) 77 JC) 0.49 mJD) 1.8 mJE) 9.2 mJ
Q:
An RLCcircuit has a capacitance of 12 F, an inductance of 25 mH, and a resistance of 60 . The current oscillates with an angular frequency of:A) 1.2 x103rad/sB) 1.4 x103rad/sC) 1.8 x103rad/sD) 2.2 x103rad/sE) 2.6 x103rad/s
Q:
The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLCcircuit might due to:
A) a large inductance
B) a large capacitance
C) a small capacitance
D) a large resistance
E) a small resistance
Q:
An RLCcircuit has a resistance of 200 and an inductance of 15 mH. Its oscillation frequency is 7000 Hz. At time t= 0 the current is 25 mA and there is no charge on the capacitor. After five complete cycles the current is:A) 0 AB) 1.8 x10-6AC) 2.1 x10-4AD) 2.3 x10-3AE) 2.5 x10-2A
Q:
An LCcircuit has a capacitance of 30 F and an inductance of 15 mH. At time t= 0 the charge on the capacitor is 10 C and the current is 20 mA. The maximum current is:A) 15 mAB) 20 mAC) 25 mAD) 35 mAE) 42 mA
Q:
An LCcircuit has a capacitance of 30 F and an inductance of 15 mH. At time t= 0 the charge on the capacitor is 10 C and the current is 20 mA. The maximum charge on the capacitor is:A) 8.9 CB) 10 CC) 12 CD) 17 CE) 24 C
Q:
At time t= 0 the charge on the 50-F capacitor in an LCcircuit is 15 C and there is no current. If the inductance is 20 mH the maximum current is:A) 15 nAB) 15 AC) 6.7 mAD) 15 mAE) 15 A
Q:
The total energy in an LCcircuit is 5.0 x10-6J. If L= 25 mH the maximum current is:A) 10 mAB) 14 mAC) 20 mAD) 28 mAE) 40 mA
Q:
The total energy in an LCcircuit is 5.0 x10-6J. If C = 15 F the maximum charge on the capacitor is:A) 0.82 CB) 8.5 CC) 12 CD) 17 CE) 24 C
Q:
An LCcircuit has an inductance of 20 mH and a capacitance of 5.0 F. At time t= 0 the charge on the capacitor is 3.0 C and the current is 7.0 mA. The total energy is:A) 4.1 x10-7JB) 4.9 x10-7JC) 9.0 x10-7JD) 1.4 x10-6JE) 2.8 x10-6J
Q:
In an oscillating LCcircuit, the total stored energy is Uand the maximum charge on the capacitor is Q. When the charge on the capacitor is Q/2, the energy stored in the inductor is:
A) U/2
B) U/4
C) (4/3)U
D) 3U/2
E) 3U/4
Q:
In an oscillating LCcircuit, the total stored energy is U. The maximum energy stored in the capacitor during one cycle is:A) U/2B) C) UD) U/(2)E) U/
Q:
A capacitor in an LCoscillator has a maximum potential difference of 15 V and a maximum energy of 360 J. At a certain instant the energy in the capacitor is 40 J. At that instant what is the emf induced in the inductor?A) 0 VB) 5 VC) 10 VD) 15 VE) 20 V
Q:
A capacitor in an LCoscillator has a maximum potential difference of 15 V and a maximum energy of 360 J. At a certain instant the energy in the capacitor is 40 J. At that instant what is the potential difference across the capacitor?A) 0 VB) 5 VC) 10 VD) 15 VE) 20 V
Q:
An LCcircuit has an inductance of 20 mH and a capacitance of 5.0 F. If the charge amplitude is 40 C, what is the current amplitude?A) 0.025 AB) 0.13 AC) 1.0 AD) 7.9 AE) 400 A
Q:
A charged capacitor and an inductor are connected in series. At time t= 0 the current is zero, but the capacitor is charged. If T is the period of the resulting oscillations, the next time, after t= 0 that the current is a maximum is:
A) T/4
B) T/2
C) T
D) 3T/2
E) 2T
Q:
A charged capacitor and an inductor are connected in series. At time t= 0 the current is zero, but the capacitor is charged. If T is the period of the resulting oscillations, the next time, after t= 0 that the charge on the capacitor is a maximum is:
A) T/4
B) T/2
C) T
D) 3T/2
E) 2T
Q:
An LCseries circuit with an inductance Land a capacitance Chas an oscillation frequencyf.If we now take two of those inductors, each with inductance L, and two of the capacitors, each with capacitance C, and wire them all in series to make a new circuit, its oscillation frequency will be:
A) f/4
B) f/2
C) f
D) 2f
E) 4f
Q:
Radio receivers are usually tuned by adjusting the capacitor of an LCcircuit. If C= C1for a frequency of 600 kHz, then for a frequency of 1200 kHz one must adjust Cto:
A) C1/2
B) C1/4
C) 2C1
D) 4C1
E)
Q:
In the circuit shown, switch S is first pushed up to charge the capacitor. When S is then pushed down, the current in the circuit will oscillate at a frequency of: A) 0.010 Hz
B) 12.5 Hz
C) 320 Hz
D) 2000 Hz
E) depends on V0
Q:
An LCcircuit has an oscillation frequency of 105Hz. If C = 0.1 , then L must be about:A) 10 mHB) 1 mHC) 25 D) 2.5 E) 1 pH
Q:
An LCcircuit consists of a 1 capacitor and a 4 mH inductor. Its oscillation frequency is approximately:A) 0.025 HzB) 25 HzC) 60 HzD) 2500 HzE) 16,000 Hz
Q:
We desire to make an LCcircuit that oscillates at 100 Hz using an inductance of 2.5 H. We also need a capacitance of:A) 1 FB) 1 mFC) 1 D) 1 nFE) 1 pF
Q:
Which of the following has the greatest effect in decreasing the oscillation frequency of an LCcircuit? Using instead:
A) L/2 and C/2
B) L/2 and 2C
C) 2Land C/2
D) 2Land 2C
E) none of these
Q:
A 150-g block on the end of a spring with a spring constant of 35 N/m is pulled aside 25 cm and released from rest. In the electrical analog the maximum charge on the capacitor is 0.25 C. The maximum current in the LCcircuit is:
A) 0.025 A
B) 0.12 A
C) 3.8 A
D) 5.3 A
E) 40 A
Q:
A 150-g block on the end of a spring with a spring constant of 35 N/m is pulled aside 25 cm and released from rest. In the electrical analog the initial charge on the capacitor is:
A) 0.15 C
B) 0.25 C
C) 8.8 C
D) 15 C
E) 35 C
Q:
Consider the mechanical system consisting of two springs and a block, as shown. Which one of the five electrical circuits (I, II, III, IV, V) is the analog of the mechanical system? A) I
B) II
C) III
D) IV
E) V
Q:
The electrical analog of a spring constant kis:
A) L
B) 1/L
C) C
D) 1/C
E) R
Q:
A charged capacitor and an inductor are connected in series. At time t= 0 the current is zero, but the capacitor is charged. If T is the period of the resulting oscillations, the next time, after t= 0 that the energy stored in the electric field of the capacitor is a maximum is:
A) T/4
B) T/2
C) T
D) 3T/2
E) 2T
Q:
A charged capacitor and an inductor are connected in series. At time t= 0 the current is zero, but the capacitor is charged. If T is the period of the resulting oscillations, the next time, after t= 0 that the energy stored in the magnetic field of the inductor is a maximum is:
A) T/4
B) T/2
C) T
D) 3T/2
E) 2T
Q:
A charged capacitor and an inductor are connected in series. At time t= 0 the current is zero, but the capacitor is charged. If T is the period of the resulting oscillations, the next time, after t= 0 that the voltage across the inductor is a maximum is:
A) T/4
B) T/2
C) T
D) 3T/2
E) 2T
Q:
An LCcircuit has an inductance of 15 mH and a capacitance of 10 ïF. At one instant the charge on the capacitor is 25 . At that instant the current is changing at the rate:A) 0 A/sB) 1.7 x10-7A/sC) 5.9 x10-3A/sD) 3.8 x10-2A/sE) 170 A/s
Q:
In each of the following operations, energy is expended. The LEAST percentage of returnable electrical energy will be yielded by:
A) charging a capacitor
B) charging a storage battery
C) sending current through a resistor
D) establishing a current through an inductor
E) moving a conducting rod through a magnetic field
Q:
An inductance Land a resistance Rare connected in series to an ideal battery. A switch in the circuit is closed at time t= 0, at which time the current is zero. The energy stored in the inductor is a maximum:
A) just after the switch is closed
B) at the time t= L/Rafter the switch is closed
C) at the time t= L/R2after the switch is closed
D) at the time t= 2L/Rafter the switch is closed
E) a long time after the switch is closed
Q:
The stored energy in an inductor:
A) depends, in sign, upon the direction of the current
B) depends on the rate of change of current
C) is proportional to the square of the inductance
D) has units J/H
E) is none of the above
Q:
An inductance Land a resistance Rare connected in series to an ideal battery. A switch in the circuit is closed at time t= 0, at which time the current is zero. The rate of increase of the energy stored in the inductor is a maximum:
A) just after the switch is closed
B) at the time t= L/Rafter the switch is closed
C) at the time t= 2L/Rafter the switch is closed
D) at the time t= (L/R)ln 2 after the switch is closed
E) a long time after the switch is closed
Q:
A 6.0 mH inductor is in a circuit. At the instant the current is 5.0 A and its rate of change is 200 A/s, the rate with which the energy stored in the inductor is increasing is:A) 7.5 x10-2WB) 3.0 WC) 6.0 WD) 120 WE) 240 W
Q:
Immediately after switch S in the circuit shown is closed, the current through the battery is: A) 0
B) V0/R1
C) V0/R2
D) V0/(R1+ R2)
E) V0(R1+ R2)/(R1R2)
Q:
The diagrams show three circuits with identical batteries, identical inductors, and identical resistors. Rank them according to the current through the battery just after the switch is closed, from least to greatest. A) 3, 2, 1
B) 2 and 3 tie, then 1
C) 1, 3, 2
D) 1, 2, 3
E) 2, 3, 1
Q:
An inductor with inductance Land a resistor with resistance Rare wired in series to an ideal battery with emf . A switch in the circuit is closed at time t= 0, at which time the current is zero. A long time after the switch is thrown the potential differences across the inductor and resistor are:
A) 0, B) , 0
C) /2, /2
D) (L/R), (R/L)
E) unknown since the rate of change of the current is not given
Q:
An 8.0-mH inductor and a 2.0-resistor are wired in series to a 20-V ideal battery. A switch in the circuit is closed at time t= 0, at which time the current is zero. Immediately after the switch is thrown the potential differences across the inductor and resistor are:A) 0 V, 20 VB) 20 V, 0 VC) 10 V, 10 VD) 16 V, 4 VE) unknown since the rate of change of the current is not given
Q:
An 8.0-mH inductor and a 2.0-resistor are wired in series to a 20-V ideal battery. A switch in the circuit is closed at time t= 0, at which time the current is zero. After a long time the current in the resistor and the current in the inductor are:A) 0 A, 0 AB) 10 A, 10 AC) 2.5 A, 2.5 AD) 10 A, 2.5 AE) 10 A, 0 A
Q:
An inductance L, resistance R, and ideal battery of emf are wired in series. A switch in the circuit is closed at time t= 0, at which time the current is zero. At any later time tthe emf of the inductor is given by:A) (1 - e-Lt/R)B) e-Lt/RC) (1 + e-Rt/L)D) e-Rt/LE) (1 - e--Rt/L)
Q:
An inductance L, resistance R, and ideal battery of emf are wired in series and the circuit is allowed to come to equilibrium. A switch in the circuit is opened at time t= 0, at which time the current is /R. At any later time tthe potential difference across the resistor is given by:A) (1 - e-Lt/R)B) e-Lt/RC) (1 + e-Rt/L)D) e-Rt/LE) (1 - e-Rt/L)
Q:
An inductance L, resistance R, and ideal battery of emf are wired in series and the circuit is allowed to come to equilibrium. A switch in the circuit is opened at time t= 0, at which time the current is /R. At any later time tthe current iis given by:A) (/R)(1 - e-Lt/R)B) (/R)e-Lt/RC) (/R)(1 + e-Rt/L)D) (/R)e-Rt/LE) (/R)(1 - e-Rt/L)
Q:
When the switch S in the circuit shown is closed, the time constant for the growth of current in R2is: A) L/R1
B) L/R2
C) L/(R1+ R2)
D) L(R1+ R2)/(R1R2)
E) (L/R1+ L/R2)/2
Q:
If both the resistance and the inductance in an LRseries circuit are doubled the new inductive time constant will be:
A) twice the old
B) four times the old
C) half the old
D) one-fourth the old
E) unchanged
Q:
An inductance L, resistance R, and ideal battery of emf are wired in series. A switch in the circuit is closed at time t= 0, at which time the current is zero. At any later time tthe potential difference across the resistor is given by:A) (1 - e-Lt/R)B) e-Lt/RC) (1 + e-Rt/L)D) e-Rt/LE) (1 - e-Rt/L)
Q:
An inductance L, resistance R, and ideal battery of emf are wired in series. A switch in the circuit is closed at time t= 0, at which time the current is zero. At any later time tthe current iis given by:A) (/R)(1 - e-Lt/R)B) (/R)e-Lt/RC) (/R)(1 + e-Rt/L)D) (/R)e-Rt/LE) (/R)(1 - e-Rt/L)
Q:
An 8.0-mH inductor and a 2.0-resistor are wired in series to an ideal battery. A switch in the circuit is closed at timet= 0, at which time the current is zero. The current reaches half its final value at a time of:A) 2.8 msB) 4.0 msC) 3.0 sD) 170 sE) 250 s
Q:
The diagram shows an inductor that is part of a circuit. The direction of the emf induced in the inductor is indicated. Which of the following is possible? A) The current is constant and rightward
B) The current is constant and leftward
C) The current is increasing and rightward
D) The current is increasing and leftward
E) None of the above
Q:
An inductor with inductance Land an inductor with inductance 2Lare connected in parallel. When the rate of change of the current in the larger inductor is 2000 A/s the rate of change of the current in the smaller is:
A) 400 A/s
B) 1000 A/s
C) 1600 A/s
D) 2000 A/s
E) 4000 A/s
Q:
A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. When the total emf of the combination is 16 V, the rate of change of the current in the larger inductor is:A) 2.0x103A/sB) 3.6x103A/sC) 4.6 x103A/sD) 7.0 x103A/sE) 8.1 x103A/s
Q:
A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. The equivalent inductance is:
A) 0.13 mH
B) 0.51 mH
C) 1.0 mH
D) 2.0 mH
E) 8.0 mH